Small project #14 — KIS-3R33S breakout — with citrus smell !

Not “pining for the fjords”, but pining for the boards!

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Hey, what is THIS?

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The perils of international shipping?

Well, the postman was a bit puzzled, and so am I. I was suspecting that some liquid came in touch with the letter, but when I opened it, the circuit boards were literally drenched in it!

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What is it? I DO NOT KNOW, but it has a distinctive citrus note. Is it some sort of cleaning agent? Anyhow, I used gloves, liquid soap and IPA to remove it thoroughly.

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Assembly was straight forward, with two notable exceptions:

1) as the board is pretty packed with parts, it was NOT advantageous to solder the trimmer first: NO ACCESS to the capacitor. Removing the trimmer resulted in some superficial heat damage to it (hot air gun). I ended up using ChipQuik (low-melt solder).

2) having placed the trimmer and capacitor first almost blocked access to half of the pads of the DC-DC module (KIS-3R33S). Again, I was saved by proper gear! Fortunately my Weller WSM 1 comes with an exceptionally tiny WMRP soldering pen (2mm chisel type).

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Result of a short & superficial test: voltage adjustment (no load) works as expected.

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Glamour shot:

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A bit of testing:

Output voltage AC ripple, no load, 20mV/div. Not too bad.

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Output voltage AC ripple, 3A load, 20mV/div. Not too bad.

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Input voltage AC ripple, 3A load, 200mV/div. Typical for buck, current ramping up and down.

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A-meter + scope.

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Test setup. Power is supplied by a 12V lead-acid battery, off camera due to size. Yes, the wires are a bit thin. I just wanted to see if the device would release the magic blue smoke, didn’t happen ;-)

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Design files and so forth

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